This description relates to electronic interfacing with a head-mounted device.
Audio signals, for example, are typically carried to a headphone through a multiple-conductor cable ending in a plug that fits into a jack of a player or radio. When a microphone is added to the headphone to form a headset, the microphone signal also may be carried through the same cable to a device that uses the microphone signal, such as a telephone set or a recorder. In aviation headsets, the cable may be detachable at a jack on the headset to permit changes in the use of the headset.
The connecting cable may also be disconnected from typical noise reduction headphones when the user is using only the noise reduction feature and is not using audio from a player or radio. The circuits that are part of noise reduction headphones may be powered by batteries mounted in the headphones.
In some military communication headsets, a detachable microphone plug may both carry the microphone signal to an intercom circuit and microphone power.
Headsets that can be plugged into cell phones for hands-free use commonly use electret microphones that receive bias voltage from the cell phone's power source.
Portable music players may provide power to run electronics in peripheral devices such as transmitters to an FM radio in, for example, an automobile.
In the Universal Serial Port (USB) standard, power may be provided by a USB host or hub to a USB peripheral through a USB connector. The host and peripheral may exchange messages (using the USB standard's handshaking and power management features) regarding one another's identity and operational parameters. The messages may include how much power the peripheral will use in different operational states or the amount of memory available in the peripheral. USB headsets may be configured as peripherals in interaction with other devices.